1. Field of the Invention
This invention pertains to the field of clutch-engaging mechanisms. More particularly, it is a device for rapidly engaging and disengaging a clutch in an engine-powered, wheeled vehicle to provide power to the drive wheels without shifting to a higher gear ratio (lower gear).
2. Description of the Prior Art
An engine is generally defined as a device for converting one form of energy into another, usually into mechanical motion. A windmill converts wind velocity to rotary or reciprocating mechanical motion; an electric motor converts electricity to mechanical energy, and a combustion engine converts the chemical energy of a fossil fuel to mechanical motion. In the conversion of hydrocarbon fuel, such as gasoline, to the rotary mechanical motion of the drive wheels, such as in an automobile or motorcycle, the internal combustion engine displays the characteristic of outputting torque or power as a direct function of engine speed or revolutions per minute (rpm) of the engine crankshaft.
It is common to interpose a device, called a transmission, between the engine output shaft and the drive wheel axle in order to change the ratio of turns of the engine shaft to turns of the axle so that the appropriate amount of torque may be provided to the drive wheels for a given situation. For instance, in starting a vehicle from a stop or turning it through a curve, a large amount of torque is needed at the drive wheels. The ratio of shaft to axle-turning rate is raised to allow more engine shaft turns per turn of the axle to provide this increase in required torque; this is generally described as shifting to a "lower gear" even though the ratio is large, such as 16 turns of the engine shaft per turn of the axle. In contrast, in high-speed cruise, the ratio is lowered to allow fewer turns of the shaft per turns of the axle, such as a ratio of four-to-one, to provide the appropriate torque to the drive wheels while preventing the engine from over-speeding. The gear ratio changes are made in the transmission which is a box or container of various diameter gears that are intermeshed in these various ratios through the use of levers.
A clutch is interposed between the engine shaft and the transmission. Its function is to disconnect, on command, the shaft from the transmission gears to allow them to be moved about inside the transmission free of mechanical stress applied from the engine. As is commonly practiced, one disengages or opens the clutch prior to shifting the gears in the transmission and then engages or closes the clutch after shifting is accomplished to re-connect the engine, through the transmission, to the drive wheels.
In the field of motorcycles, the engine is made quite small for various reasons, including reducing the overall weight of the motorcycle and presenting a small silhouette to lessen wind resistance. The characteristic of low-torque at low-engine rpm--high-torque at high-engine rpm is particularly noticeable in these small engines mainly because of the smaller overall engine size and the inherently reduced diameter of the cylinders where conversion of fuel energy to mechanical energy takes place. Much shifting is therefore needed to provide the appropriate torque for the particular situation encountered by the motorcycle driver.
In racing motorcycles, time is quite precious; seconds or parts of seconds may spell the difference between winning or losing. Much effort is expended to reduce the time involved in engine speed changes or transmission shifting to permit engine torque to be applied to the drive wheel for as long a time as possible. When the motorcycle is cruising in a straight path, where high speed is obtained through a low-gear ratio, and thereafter directed out of that straight path into a turn, increased torque is needed to power it into and through the curve. Down shifting to a higher engine shaft to drive-axle ratio requires the time-consuming job of disengaging the clutch, shifting the transmission gears, lowering the engine speed and re-engaging the clutch. This is a time-wasting procedure.
A method of obtaining the required amount of torque without resorting to the time-consuming shifting operation has been discovered wherein the rider rapidly activates the handle bar-mounted clutch disengagement-engagement lever through a series of disengagement-engagement cycles while maintaining the throttle open to provide the highest engine speed. When the clutch is disengaged, i.e., the clutch handle is squeezed, the engine races at high rpm. Without shifting out of the low engine shaft to axle ration ("high" gear), the clutch is rapidly engaged, i.e., the handle is released and the energy is transmitted from the high-speed engine through the transmission to the rear drive wheel. Because the gear ratio is still quite low, the engine quickly loses rpm and the torque or power delivered to the drive wheel rapidly diminishes. By quickly squeezing the clutch lever, the engine is free to rapidly speed up and gain further momentum. Accordingly, by continuing to cycle the clutch at high-engine rpm will provide a stream, albeit in short-lived parcels, of energy to the drive wheels and the necessary torque to power the motorcycle through the turn or other power-requiring maneuver without undergoing the time-consuming transmission gear-changing operation. This cycling operation has proven successful in motorcycle racing.
Unfortunately, the rapid cycling of the clutch handle is distracting to the motorcycle racer because it takes some of his/her attention away from steering the vehicle through the curve. Such a loss of attention may create a hazard to the safe-handling of the motorcycle in the stressful and tension-filled activity taking place on the racetrack. A slight miscalculation, by the driver, may cause the loss of motorcycle position in the race that will undo the advantage gained by the clutch-cycling process.